With the discovery of RNA interference in 1998, small interfering RNAs (siRNAs) have been used to silence many genes in vivo and hold tremendous therapeutic potential in numerous clinical applications (Gavrilov, Yale Journal of Biology and Medicine, 85(2):187 (2012)). However, siRNAs are unstable and are degraded by serum enzymes and intracellular RNAses. In addition, sustained siRNA silencing within a cell requires repeated siRNA administrations due to intracellular degradation of these molecules (Gavrilov, Yale Journal of Biology and Medicine, 85(2):187 (2012), Whitehead, Nat Rev Drug Discov, 8(2):129-38 (2009)). In addition, siRNAs cannot diffuse readily across the cell plasma membrane due to their large size and negative charge. A number of siRNA delivery platforms have been explored, but these platforms are often limited by poor efficacy, high cytotoxicity, or lack of sustained release. To address these limitations, a safe and effective siRNA delivery platform is needed.
Therefore it is an object of the invention to provide an effective, nontoxic, and sustained release delivery system for nucleic acids such as siRNA.